Many modern electronic devices include wireless communications circuitry. For example, an electronic device may include wireless local area network (WLAN) circuitry, cellular communications circuitry, or the like. While wireless communications circuitry allows electronic devices to communicate with one another, such functionality generally comes at the cost of additional energy consumption and thus reduced battery life. As wireless communications protocols evolve to provide higher speeds, energy consumption of wireless communications circuitry often increases to meet the higher demands of such protocols. Often the transmit power amplifier (PA) within the wireless communications circuitry is the largest consumer of energy in an electronics device.
For example, the WLAN 802.11 standards and the cellular Long Term Evolution (LTE) standards use orthogonal frequency division multiple access (OFDMA) for wireless transmissions. These OFDMA wireless transmissions have a high peak to average power ratio (PAPR). When a PA using a fixed supply signal amplifies a modulated signal having a high PAPR, the PA efficiency may be greatly reduced. Envelope tracking may be used to increase the efficiency by modulating the supply signal to the PA based on the modulation envelope of the modulated signal. A look-up-table (LUT) may be populated with values during factory calibration to shape the magnitude of supply signal modulation versus input power to the PA. As temperature varies, the PA characteristics may change resulting in non-linear distortion and/or reduced PA efficiency from using supply signal modulation based on factory calibration LUT values.